Highly absorbent pressure dressing for wounds

ABSTRACT

A non- woven dressing is provided for human (or animal) body lesions which has a high rate of absorbency irrespective of gravity for water and blood, is non-compressible relative to prior art dressings to the extent that pressure generated by strips of retaining material is effectively transmitted to the wound surface, is substantially non-elastic, so that said transmitted pressure is distributed evenly when the dressing is affixed to a surface which is curved, and the material is relatively dense, to the extent that the absorbed exudates become so thinly dispersed that their adhesive effect is reduced sufficiently within the dressing material to allow layers of said material to be readily separated one from another at any time.

United States Patent 1191 Carlisle [45 July 23, 1974 HIGHLY ABSORBENT PRESSURE 3,639,199 2/1972 Brandtsetal 128/284 x DRESSING FOR WOUNDS 3,658,790 4/1972 Bernardin 128/284 X 3,663,348 5/l972 Liloia et al 128/284 X Inventor: Richard Carllsle, Beechwood 3,670,731 6/1972 Harmon 128/156 x Box 307, Rye, NY. 10580 22 Filed; 17 1971 Primary Examiner-Richard A. Gaudet Assistant ExaminerJ. Yasko [21] Appl. No.2 199,759

Related US. Application Data [57] ABSTRACT [63] Continuation-impart of Ser. No. 877,823, Nov. 18, A woven dressing is id for human (or i 1969 abandoned mal) body lesions which has a high rate of absorbency irrespective of gravity for water and blood, is non- [22] 8|. ll28/156 compressible relative to prior art dressings to the tent that pressure generated strips of retaining 1 0 can 128/156 terial is effectively transmitted to the wound surface, 128/296 2681 89 is substantially non-elastic, so that said transmitted pressure is distributed evenly when the dressing is af- [56] References cued fixed to a surface which is curved, and the material is UNI STATES PATENTS relatively dense, to the extent that the absorbed exu- 3,301,257 1/1967 Crowe, Jr. et a1. 128/156 X dates become so thinly dispersed that their adhesive 3,430,629 3/1969 Murphy 128/284 effect is reduced sufficiently within the dressing mate- 3,441,021 1969 Endres 156 rial to allow layers of said material to be readily sepa- 3,52l,632 7/1970 Graham 128/268 X rated one f another at any i 3,543,756 12/1970 Murphy 128/284 3,545,442 12/1970 Wicker et al. 128/156 X 18 Claims, 3 Drawing Figures 1 HIGHLY ABSORBENT PRESSURE DRESSING FOR WOUNDS This is a continuation in part of my co-pending application Ser. No. 877,823 of Nov. 18, 1969 now abandoned.

FIELD OF THE INVENTION DESCRIPTION OF PRIOR ART Previous surgical dressings have been primarily intended to keep a wound clean and dry, so as to protect it during the healing process. In addition, published studies (Twyman, Brown et al) have indicated an advantageous use of dressings which maintain pressure on a wound surface during healing. Results have shown acceleration of the healing process and improvement in the quality of the repair, or granulation tissue. In order to apply pressure during a healing process, large bulky pressure dressings are generally utilized. These involve extra time for installation, and much skill on the part of the doctor or nurse, because more than one layer of thick, bulky cottondressings are affixed with extensive quantities of adhesive tape. This combination is critical, because either too much'or too little pressure can To determine pad compressibility, or softness, of the various dressing materials under consideration, I measured the amount of decrease in thickness of a given dressing-material when compressed by a starting pressure of 0.1 ounce per square inch, and a final pressure of 7 pounds per square inch. In order to bring the layers of a dressing into apposition for measuring the uncompressed thickness, I found it necessary to place upon 7 them the small starting pressure of 0.1 ounce per square inch. I calculated the final pressure of 7 pounds per square inch as the maximal pressure which narrow strips of retaining tape can be expected to exert on the surface of a dressing when applied with high tension. The softness of the prior art dressing materials is such that under a compression factor of 7 pounds per square inch, the materials were reduced in thickness over 50 percent of their original, uncompressed state. My dressing material, when similarly compressed, becomes reduced in thickness only approximately 30 percent. I calculate a maximum compression limit for a dressing material suitable for this invention to be 43 percent when it is compressed in accordance with this method.

1 A preferred range of compressibility for my material is result from improper use of the adhesive tape. Wrapping with too many layers would produce too much pressure and restrict circulation; wrapping with insufficient layers would result in too little pressure. When the dressings are applied correctly, they are at best clumsy, occlusive, and difficult to remove and redress at prescribed dressing change intervals.

: SUMMARY OF THE INVENTION While experimenting with a wide variety of absorbent materials, I found, unexpectedly, that by using a relatively firm material, that is, material as firm as, orfirmer than the flesh to which it is applied, that effective pressure dressings can be constructed using layers of such firm material having a total thickness of less than one half the total thicknesses required for standard soft,re-

silient materials like surgical cotton, cotton gauze,-

body surface. A material that resists compression will not collapse and will remain relatively thick, or high I from the body surface, when strips of retaining material are fastened over it and down to the body surface. This allows the retaining tape strips to form a desired greater angle, required for increased pressure application. Thus, a relatively non-bulky pressure dressing is provided, which can be applied readily and will cause less inconvenience for the patient.

between 20 percent and 35 percent. The lower value of 20 percent is optimal when the dressing is adapted to be applied to wounds with anticipated high exudation rates. In such cases, the dressing becomes thoroughly saturated within a few hours. However, the material will retain its thickness, and ability ,to transmit pressure, after such saturation occurs, if the material has its compressibility limited to the value of approximately 20 percent. For wounds with slight exudation, where the dressing does not become totally saturated, it is aesthetically preferable to impart a greater degree of softness to the dressing. For these instances, higher valuesup to 35 percent are recommended.

The material of my invention is relatively resistant to elongation in all directions. Assuming a test strip one inch wide by three inches long, laminated to a total thickness of, for example, one thirty-second inch (measured when compressed with 7 pounds per square inch) two pounds force (orslightly more) are required to stretch the material 10 percent of its original length. Greater force is required in proportion to thickness of material. In contrast, surgical gauze and other standard dressing materials elongate much more, particularly in the diagonal directions of a cross weave material. My material is firm and non-woven, and resists elongation in all directions with no diagonal weakness. Furthermore, if the material is stretched to its breaking point, the elongation will not exceed 20 percent. The resistance to elongation of this material provides an unexpected advantage inregard to pressure distribution. I found, when a dressing of this material is affixed to a surface having slight convex or concave cylindrical curvature, the resultant curvature of the dressing will impart a marked degree of rigidity to the entire dressing, whether it is circular, oval, or polygonal in shape. This is very important in regard, to distribution of the pressure generated by strips of retaining material affixed over a dressing applied to a curved portion of a patients body. For instance, a 3 inch by 8 inch dressing can be applied to a patients arm or leg using only two strips of one inch width adhesivetape, and the resultant pressure on a given wound, such as a large area burn, will be distributed substantially evenly over the entire area covered by the dressing. In contrast, a standard 3 gauze dressing material would. require strips of tape covering approximately twice as much area of the dressing to achieve the same degree of pressure distribution. A woven gauze dressing, due to its easily diagonally elongated nature, has relatively little ability to laterally distribute pressure generated by strips of retaining material. v

In summary, the relatively non-compressible character of my dressing material enables strips of retaining material to transmit increased pressure through the dressing to a body surface, and the materials resistance to elongation results in relatively even distribution of the pressure generated by the strips of retaining material. In regard to dressing manageability, including removal, inspections, etc my dressing offers unique advantages. Due to the high density of the material, (such that particles having a diameter greater than 25 microns are barred from passage through the fibrous .Fluid absorption characteristics have been thoroughly considered in my invention. Speedof absorption, direction of absorption,"and the length of wicking .period are each fundamentally important. To compare absorption speed and wicking durability of dressing materials, l inch wide strips 12 inches in length, of the materials to be tested are simultaneously dipped into a reservoir of distilled water, tinted lightly with ink or structurelan absorbed exudate is dispersed thinl y O food coloring. The strips are hung vertically, maintaining approximately the first one-half inch of the strips under the surface of the liquid. The distance which the liquid travels upward against gravity is measured after 1 minute, minutes, minutes, minutes, 60 minutes, 120 minutes, and 1,440 minutes.

The following results compare my dressing material (B), with surgical cotton gauze (A):

msrAncesxs'siifiib svrwo DIFFERENT MATERIALS VERTICALLY AGAINST GRAVITY throughout individual layers of the dressing withFoin cident reduction of interlayer adhesion. Thus, said layers are adapted to be removed individually or several at a time, whether an absorbed exudate is wet or dry. A novel technique has evolved during the testing of this dressing, whereby one or two layers of a dressing are left on the wound during a dressing change as part of the scab. A new dressing can be applied directly over them. When separating the layers, it is procedure to hold down the top layer of those layers-which are to be left on the wound, and lift off the layers which are to be removed, with tweezers, fingertips, or the like.

In cases where one or two unchanged layers are left on a wound for periods of two or more weeks, results have shown that complete healing can occur with excellzmt cosmetic results. and with no evidence of dressing fibers becoming involved with granulating, or healing. tissues. This is apparently due to the dressing materials fibrous structure having a porousity characteristic such that particles having a diameter of more than 25 microns are barred from passage therethrough. Thus,

2o so so 120 TIME (MINUTES) It isappaem tliatthe csitoagau'i material reaches a over 80 percent of its final absorption distance after 10 minutes. My material continues to absorb steadily (i.e. wick) until it reaches a height approximately double that reached after 10 minutes. It is also apparent that there is a marked differential in the absorption speeds from the start. The ability of my material to continue j wicking for many hours is a very important factor, as

1 greater than 12 hours. Thus, an exuding wound will bethe finely porous, highly dense fibrous construction of the material provides the dual advantages of dispersing absorbed exudates to a low interlayeradhesion level,

and preventing healing tissues from becoming entangled with the material.

dressing changes are'normally performed at intervals of maintained continuously at a more constant moisture level during the entire interval between dressing changes when a dressing with a long wicking period is employed.

l BRIEF DESCRIPTION OF DRAWINGS FIG. 1 ariexploded, enlarged, cross-sectional view of the layers of a wound dressing with a joining stitch according to the principles of this invention.

FIG. 2 is a view of the dressing of FIG. 1 after flexure 5 around a portion-of the body, and

FIG, 3 is an enlarged cross-sectional view of the dressing taped to a portionof, the body.

. DESCRIPTION OF THE PREFERRED I EMBODIMENTS Referring to the drawings, in FIG. 1, the numbers to 14 inclusive refer to sucessive layers of embossedpaper, in which the Outer layers 10 and 14 are less deeply embossed'than the inner layers 11,12, and 13. The layers are fastened together by a loop of which the portion 15 is shown.

In FIG. 2, the ends of the layersare flexed and slid to fit a portion of the body, and the loop 15 continues to fasten-the layers together while permitting flexure.

In FIG. 3, the layers are affixed to a portion of the body 18 and and retained by tape 17, applied with high tension. The respective layers are only slightly deformed by the pressure of the tape, whereas when standard dressing material such as cotton gauze is.

us ed the relative deformation is mgh greater. WM The material preferably used for the construction of;

the present invention is short fiber hard wood pulp 20? nique used to produce the Scott toweling is described' in US. Pat. No. 2,834,809. The material is somewhat perforated duringembossing, which enhances its absorptivity in regard to speed and total liquid capacity. To form a dressing, multiplelayers (3 to 50) of the material are assembled and pressed with heat and moisture, sufficiently to firm up the material (so that it will not reduce in thickness more than 43 percent .if later compressed under a pressure of 7 pounds per square Secondly, the dressing material can be presaturated with water or a water-base disinfectant several minutes before a dressing removal procedure, if it is desired to remove all layers of the dressing from a wound How ever, if it is desired to remove the entire dressing without presaturation, an alternate construction is recommended. This consists of providing a wound contacting layer of woven ornon-woven material having apertures such that particles having a diameter of greater than microns will be allowed to pass therethrough. Preferably, a sheer layer of a plastic material such as perforated polyethylene film or polyethylene netting is used, having a thickness of less than 0.015 inch. Such a wound contacting layer can be fastened to one or both inch), and to smooth the outer surfaces of the lami-.

nated material. The material is then cut to desired shapes with a die or other suitable means. The next procedure is to fasten the layers together by suitable means, so as to allow flexure and interlayer sliding when the dressing is applied to a curved surface. A loosely looped stitch of thread 15, or Small pieces of overlapped adhesive material, or crimping, can be utilizedso as to retain the layers in aslidable,substantially superimposed relationship. If crimping is utilized, it is done in such a way that the crimped regions will hold tightly enough so as to stay intact until such time that the dressing is applied to a curved portion of a patients body. When the dressing is affixed over a curved surface, the crimped regions will break free and allow interlayer sliding as the dressing conforms to said curved surface. This dressing, when complete, can be packaged and then autoclaved (steam sterilization) or sterilized with any one of several types of gas or other sterilization means. i

An alternate construction is advantageous for-in stances where the entire dressing must be removed from a wound when dry. The dressing, as described, can be managed in at least two ways in regard to re-' moval from a wound. First, one or more layers can be left on the wound as stated earlier in this specification.

outer surfaces ofthe dressing, or such material could take the form of a surrounding envelope. The latter 1 construction can be used to retain all the layers of the dressing in a substantially superimposed, slidable relajtionship, and eliminate the need for other interlayer fastening means. Similarly, two separate layers of thermoplastic netting can be placed respectively on each outer surface of an assemblage of layers ofthe dressing material, the netting having dimensions which provide overlapping peripheral regions which would then be cemented or heat sealed around the periphery of the dressing material, thus forming a suitable envelope to retain the dressing layers in a substantially superimposed, slidable relationship. The latter construction is well adapted for established production techniques.

Footnotes:

" E.D. Twyman, M.D., "Epithelial Proliferation. Differential Pressure as an Aid in the Growth of Epithelium on a Denuded Surface". Journal Missouri State Medical Society, XIX (1922) p. 257, 258.

James Barrett Brown, M.D., and Frank McDowell. M.D., Skin Grafling, J.B. Lippincott Company, Philadelphia, 1958 (Third Edition).

Pressure dressings are fundamental in the preparation of wounds for skin grafting. This continuous pressure probably does most to convert edematous, pinkish-gray,- course granulationsinto firm, bright-red, fine ones. The pressure is applied by the external bandages which should be large and heavy enough for the purpose.

. I claim:

' 1. A dressing for wounds substantially constructed from cellulosic material, formed in thin layers, adapted to be applied to curved surfaces by interlayer-sliding means, said dressing having limited compressibility reduces the dressing thickness no more than 40 percent of its thickness when compressed by a pressure of one tenth ounce per square inch.

2. A dressing according to claim 1, whereby the material has a resistance to elongation in all directions, such that more than 2 pounds of force are required to impart a 10 percent elongation in a strip of the material 1 inch wide by 3 inches long having a thickness of one thirty-second inch.

3. A dressing according to claim 1, whereby layers of the material have resistance to elongation in all directions, such that they do not elongate more than 20 percent of their original length if stretched to their breaking point in a given direction.

i 4. A dressing according to claim 1, whereby layers of the dressing material can absorb distilled water vertically against gravity continuously for more than 5 hours, the final height attained by said water in a given layer equal to more than percent of the height reached by said water in said layer after '10 minutes. allow passage of particles having a diameter of more A 5. A dressing according to claiml, whereby layers of than 25 microns.

the dressing material have a fibrous structure suffi- 13. A dressing as in claim 1, having means to mainciently dense such that an absorbed exudate becomes tain layers of said cellulosic material superimposed in thinly dispersed with coincident reduction of interlayer a manner which allows interlayer sliding to occur when adhesion, whereby the layers-are adapted for removal the dressing is flexed.

individually while a portion of the layers is held down. I 14. A dressing as in claim 13, wherein said means is l i at least one loosely looped, stitched filament.

dressing 80601 g to claim hereby the'lay-I 15. A dressing as in claim 13, wherein said means is ers of cellulosic material are comprised substantially of i atvleast one ll i e f overlapped dh i matewood pulp produced by chemical means. i i L' A dressing according to Claim 6, whereby layers of? 16. A dressing as in claim 13, wherein said means is the cellulosic material are provided withwet strength; crimping by the addition of at least one resinous material- 17. A dressing for wounds containing layers of very A dressing according to claim l whereby a firm and relatively non-stretchable material, arranged cal wetting agent is added to provide a desired absor" to allow for interlayer sliding when applied to a curved bengy I portion of the human body, said layers necessarily slid- A dressing according to clalm having i aing relative to one another when affixed to a relatively at opposlte smifaces of the total dressing and small radius curved portion of the human body, said layers between outer at least one i ldressing, when affixed and held in place with retaining Inner layers bemg embossed Sald. layers havmg mlmaterial, adapted to exert relatively evenly a pressure crppassages between fibers wherein m a gwen l-ayer l on the wound surface which tends to improve the qualsaid passages are so small as to bar passage of particles lg of the repair tissue formed during healing, Said y in solution greater than microns in diameter.

10. A dressing according to claim 9, whereby layers 25 ers unable. to elongate m any -9 i i 20 between said outer layers are progressively more mt at leasl some. "RWl 0 Said 3 deeply embossed at intervals progressively further inv material, and said material havlng limited compressibilward f Said Outer layers at opposite'surfacea ity such that a pressure of seven pounds per square inch 11 A dressing according to claim 1, whereby I reduces the material thickness no more than 40 percent outer envelope is provided which retains the layersofi of thlcknless when compressed y a Pressure of one the dressing material in a slidable substantially super-- 7 tenth ounce P q l P imposed relationship and facilitates removal of the. 18- A r g In Clalm 17, Where"! the total dressing from a wound, ber of said layers is at least three and less than 5'1, and

12. A dressing as in claim 11, wherein said envelope said layers are substantially of cellulosic material.

is of h mop a t e l;tbaviyaazatats wh c Y 

2. A dressing according to claim 1, whereby the material has a resistance to elongation in all directions, such that more than 2 pounds of force are required to impart a 10 percent elongation in a strip of the material 1 inch wide by 3 inches long having a thickness of one thirty-second inch.
 3. A dressing according to claim 1, whereby layers of the material have resistance to elongation in all directions, such that they do not elongate more than 20 percent of their original length if stretched to their breaking point in a given direction.
 4. A dressing according to claim 1, whereby layers of the dressing material can absorb distilled water vertically against gravity continuously for more than 5 hours, the final height attained by said water in a givEn layer equal to more than 150 percent of the height reached by said water in said layer after 10 minutes.
 5. A dressing according to claim 1, whereby layers of the dressing material have a fibrous structure sufficiently dense such that an absorbed exudate becomes thinly dispersed with coincident reduction of interlayer adhesion, whereby the layers are adapted for removal individually while a portion of the layers is held down.
 6. A dressing according to claim 1, whereby the layers of cellulosic material are comprised substantially of wood pulp produced by chemical means.
 7. A dressing according to claim 6, whereby layers of the cellulosic material are provided with wet strength by the addition of at least one resinous material.
 8. A dressing according to claim 6, whereby a chemical wetting agent is added to provide a desired absorbency speed.
 9. A dressing according to claim 6, having outer layers at opposite surfaces of the total dressing and inner layers between said outer layers, at least one of said inner layers being embossed, said layers having micropassages between fibers wherein in a given layer said passages are so small as to bar passage of particles in solution greater than 25 microns in diameter.
 10. A dressing according to claim 9, whereby layers between said outer layers are progressively more deeply embossed at intervals progressively further inward from said outer layers at opposite surfaces.
 11. A dressing according to claim 1, whereby an outer envelope is provided which retains the layers of the dressing material in a slidable substantially superimposed relationship and facilitates removal of the dressing from a wound.
 12. A dressing as in claim 11, wherein said envelope is of thermoplastic material, having apertures which allow passage of particles having a diameter of more than 25 microns.
 13. A dressing as in claim 1, having means to maintain layers of said cellulosic material superimposed in a manner which allows interlayer sliding to occur when the dressing is flexed.
 14. A dressing as in claim 13, wherein said means is at least one loosely looped, stitched filament.
 15. A dressing as in claim 13, wherein said means is at least one small piece of overlapped adhesive material.
 16. A dressing as in claim 13, wherein said means is crimping.
 17. A dressing for wounds containing layers of very firm and relatively non-stretchable material, arranged to allow for interlayer sliding when applied to a curved portion of the human body, said layers necessarily sliding relative to one another when affixed to a relatively small radius curved portion of the human body, said dressing, when affixed and held in place with retaining material, adapted to exert relatively evenly a pressure on the wound surface which tends to improve the quality of the repair tissue formed during healing, said layers unable to elongate in any direction more than 20 percent without at least some rupturing of said layer material, and said material having limited compressibility such that a pressure of seven pounds per square inch reduces the material thickness no more than 40 percent of its thickness when compressed by a pressure of one tenth ounce per square inch.
 18. A dressing as in claim 17, wherein the total number of said layers is at least three and less than 51, and said layers are substantially of cellulosic material. 